Another Criticism of Ultimate Zone Rating

I’ve said before that I have my suspicions about fangraphs.com’s ultimate zone ratings (UZR). One thing that it doesn’t appear to take into account is what happens when outfielders play in very large ballparks.

I read a post today on mlbtraderumors.com about Rockies’ outfielder Brad Hawpe, and it mentioned what a terrible UZR he has. I’ve noticed before that outfielders who rated highly under the ultimate zone rating formula suddenly plummet when they move to Denver.

The reason is obvious. Ultimate zone rating looks at a player’s ability to make plays on balls hit into his zone. Here are part I and part II of Mitchell Litchman’s articles on Baseball Think Factory in which he defines his concept of Ultimate Zone Rating. (Note that part II does attempt to take park factors into account.)

The outfield at Coors Field is by far the largest in the major leagues, because in order to keep the homerun totals from being completely outrageous in that thin mile-high air, the fences are pushed way back.

As I’ve said, I’ve noticed this before and my antenna went up when I saw the post about Brad Hawpe. What really did it for me, though, was another post about how the Nationals apparently plan to start the 2010 season with a right field platoon of Willy Harris and Willie Taveras.

It doesn’t matter how many moves the Nats made this off-season — if that’s their right field platoon starting the 2010 season, it’s hard to imagine them winning even half of their games this year.

Anyone who has been following baseball the last few years knows that Willy Taveras is one of the worst offensive players, bar none, to play regularly in the major leagues in the last decade. Last year for the Reds, as their primary centerfielder, Taveras had a horrendous .275 on-base percentage and an even more horrendous .560 OPS in well over 400 plate appearances. The Great American Ballpark is generally considered a good place to hit, in part because it’s stinking hot in Cinci during the height of the Summer.

In 2008, as the Rockies’ primary centerfielder, Taveras’ OPS was an awful .604, and that was playing half his games in the park that everyone recognizes as the best hitters’ park in baseball.

Taveras runs exceptionally well, and I figured he must be a good defender in center to still be in the majors despite his obvious inability to hit even for a fleet centerfielder. I was right, sort of.

According to fangraphs.com, Taveras was a terrific centerfielder in his two years in Houston (2005 and 2006), posting UZR numbers of 9.8 and 18.0. However, in his next two years playing his home games at Coors Field (2007 and 2008), he was below average according to UZR at -4.7 and -2.2. However, upon arriving in Cincinnati in 2009, he suddenly learned how to play defense again, posting a 8.3 UZR.

Did Taveras suddenly forget how to play defense for two years in the middle of his career, or did the ballparks he played his home games in have something to do with it? Probably the latter.

I don’t feel like listing the outfield dimensions of Coors Field, Minute Maid Park and the Great American Ballpark. If you’re interested, Clem’s Baseball lists the dimensions (official and actual, at least according to Clem) of a whole bunch of the ballparks used by major league teams over the course of baseball history. (Sorry Clem — I didn’t look closely enough to be able to state whether or not you actually listed every major park ever played in. I will say this: you have listed a lot)

Suffice it to say that there is a whole lot of territory to cover playing center in Coors Field, at least compared to Minute Maid Park or the Great American Ballpark, particularly in the power allies. For what it’s worth, though, Minute Maid Park has some strange dimensions, with extremely short power allies (both less than 370 feet according to Clem) but an extremely deep straight-away center at 436 feet.

I don’t see the same kind of obvious discrepancies with Juan Pierre or Preston Wilson, the two other centerfielders who played for the Rockies and other teams since UZR began to be kept. Once again, all I can say for certain is that Willy Taveras’ UZR numbers are suspicious.